This invention relates to the monitoring of soil compaction using a compaction machine which applies periodic impact blows to the soil surface.
In one application of the invention, it is applicable to the monitoring of soil compaction by an impact compactor. The term "impact compactor", as used initially in U.S. Pat. No. 2,909,106, refers to a soil compaction machine which incorporates an out-of-round mass which produces a series of impact blows to the soil surface when towed or otherwise driven over that surface. The compactor mass of an impact compactor has multiple sides defining a series of spaced apart salient points on its periphery, each salient point being followed by a compacting face. As the impact roller is towed or moved over the soil surface, it rises up on each salient point and then falls forwardly and downwardly as it passes over that point, with the result that the following compacting face applies an impact blow to the soil surface. The action of the mass is therefore to store potential energy as it rises up on each salient point and then to deliver this energy as an impact blow.
Impact compactors as described above have been found to work well in practice in achieving high levels of soil compaction, even at substantial depths below the soil surface. However a problem which is encountered during compaction of a site is that of non-uniformity of soil and other conditions over the site, leading to non-uniform compaction over the site.